The Rosy Thrush-tanagerRhodinocichla rosea
is a beautiful and enigmatic Neotropical specialty (left, a lovely shot
of a singing male by Adam Riley of Rockjumper Tours). The species has
an oddly disjunct range, mostly along the coast, in western Mexico,
Costa Rica and Panama, Colombia, and Venezuela. It lives in pairs on or
near the ground in thick undergrowth in arid to semi-arid forests,
scrub, or overgrown habitat that has previously been cleared. Males are
slaty above and rich raspberry-red below; females are similar but the
red is replaced by orange. Pairs sing a flutey song in antiphonal duets.

Clark
(1913) was the first to suggest that this unusual bird — then known as
the "Panama Thrush-Warbler" —was a tanager. Skutch (1962) — using a
long name, "Queo," and citing habit and behavior — suggested it was
related to thrashers [Mimidae]. Eugene Eisenmann (1962) published
multiple reasons it could not be a mimid, but was most likely an
aberrant tanager. He argued that the "hyphenated English name
'Thrush-Tanager' ... seems adequately to suggest the taxonomic
uncertainty and the appearance of the bird." He agreed that "unless we
are prepared to cut up the traditional tanager family into a number of
families, there seems no over-all gain in erecting a separate monotypic
family for Rhodinocichla -- at least without anatomic basis."

We
are now in the era when "cutting up the traditional tanager family" is
underway apace. Barker et al. (2013), using genetic evidence,
"recovered 5 major lineages traditionally recognized as avian families
[one was the tanagers, Thraupidae], but identified an additional 10
relatively ancient lineages worthy of recognition at the family level."
One of those lineages that Barker et al. (2013) felt "worthy of
recognition at the family level" was Rosy Thrush-tanager, now proposed
as the sole member of the Rhodinocichlidae.

The
use of the tem "relatively ancient" by Barker et al. (2013) is curious.
Normally when taxonomists speak of "ancient" lineages, those go back to
the Eocene Epoch (about 34-56 million years ago), or at least the
Oligocene (about 23-34 mya), The lineages set out in Barker et al.
(2013, 2015) are no older than 15 mya, and some proposed as families
are as recent as 9 mya. Whether elevated all such lineages to Family
status has yet to be sorted out by the AOU and SACC.

Using
the data presented by Barker et al. (2013, 2015), we can retain the
five "traditional" families [Parulids, Emberizids, Tanagers, Grosbeaks,
Icterids] by adding just 5 new families (rather than 10), and one of
them [Calcariidae, the longspurs and allies] has already been adopted
by the AOU. Based on the evidence, though, the "most necessary" new
family is the Rhodinocichlidae. Barker et al. (2013, 2015) present
evidence that it is sister to the longspur/Snow Bunting family
[Calcariidae], and together these are sister to a huge assemblage that
includes the New World warbler [Parulidae], cardinals & grosbeaks
[Cardinalidae] and tanager [Thraupidae] families. In short, at about 14
million years old, the Rosy Thrush-tanager lineage is the oldest and
earliest of the offshoots among these New World passerines.

Rhodinocichla
does exhibit behavioral features adapted to its habitat niche, not
reported of any of other tanagers. It is sexually dimorphic. Most
distinctive is the antiphonal singing by both members of a pair. This
is characteristic of certain other tropical birds (notably a number of
tropical wrens), which skulk in the undergrowth and remain paired for
all or most of the year (Eisenmann 1962, Ridgely & Tudor 1989,
Hilty 2011). There are currently five generally accepted subspecies of
Rosy Thrush-tanager within a fragmented pattern of occurrence. Each may
be geographically isolated. To the eye the populations differ mostly in
the color of male's back, ranging from gray to blackish in a
'leap-frog' pattern (Hilty 2011).

Although large
and loud with, Rosy Thrush-tanager can be a very difficult bird to see
in the dense understory it inhabits. World birders will surely wish to
prioritize viewing this brilliant species. Currently it is not
considered at risk, but its terrestrial habits within threatened
tropical deciduous forests could mean that it faces heightened risk for
the future.